Also see AS7-1583, which allows Hibernate 3.3 to also work (as long as the entity classes are specified in the persistence.xml). To improve that, someone needs to figure out why the Hibernate 3.3 annotation scanning, is not working with the AS7 virtual file system. I would like to work on that but am busy with other things at the moment. If someone wants to help, I'll help get you started...

You will also see a class not found error in the server.log, but that can be ignored.

That is a start for using Hibernate 3.3, no promises that there won't be more issues. Its best to think of using Hibernate 3.3 on AS7, as a migration step (IMO). We are pushing hard on Hibernate 4.0 and adding AS7 support there (like using JBoss logging...).

And yes let me tell you that there are out there tons of apps that were developed on versions 3.3 3.2 and work fine and people to do a migration would like a simple clear simple path that would mean to deploy the same jar without the need to do several things in the part of the code, rather than configure the appserver to use the mentioned implementation. On a system that is now several thousands lines of code a switch of a backend framework doesn't justify the move just to improve version/new version whereas the old software have been proven to be good and work robustly. I used to have the same attitude but in the real buisness, take for example banks, they don't always follow the cutting edge of a technology. They wait to mature enough and prove it self and then they adopt it for general devel.

In case you haven't found it yet, the git repo for the jandex project is https://github.com/jbossas/jandex. The easiest way to debug all of this, would be building AS7 from source and running AS7 in your favorite IDE debugger (for hacking on AS7 source, read http://community.jboss.org/wiki/HackingOnAS7). When I debug AS7 with the Intellij editor, the sources for other projects (used by AS7), is usually a click away (click on load source link when stepping into subprojects). Also, the the AS7 project can be easily loaded into intellij by choosing "open new project" and choosing the as7 root "pom.xml".

The easiest way to proceed might be hacking in some debug logging, into the jandex project (or enabling it if its already there).